1. Field of the Invention
The present invention relates to a method for providing traffic telematics information about the route of a vehicle, which is traveling on a road system having multiple roads; the roads being interconnected between road junctions.
2. Description of the Related Art
Traffic telematics is used to pursue the objective of utilizing an available traffic infrastructure particularly efficiently, in order to prevent, for example, traffic jams, as well as instances in which vehicles are driven without any passengers or driven in search of something. In addition, traffic safety may be increased, thereby achieving a reduction in accidents as a result. The environmental impact may also be reduced by using vehicles more efficiently and optimizing travel routes. In this manner, the CO2 discharge in road traffic is particularly reduced.
Traffic telematics presently relates to individual traffic, and information about current or future routes is transmitted from vehicles to central processing units or exchanged by vehicles among themselves. The exchange of information, that is, the practice of provision of information by the vehicle, is based on different standards. In this context, the different standards have different sizes of data sets, and the objective of transmitting, as efficiently as possible, transmission of included information content regarding the probable future microscopic vehicle route, is pursued. The microscopic vehicle route relates to the vicinity of the vehicle, for example, direct roads or surrounding road paths, including possible road junctions, such as intersections or junctions.
A known method for describing the future vehicle route, which is also referred to, in the microscopic traffic range, as the upcoming vehicle trajectory or probable path, relates to the use of a coordinate sequence. The vehicle trajectory may be approximated using this frequency of coordinates (coordinate tuple), since the coordinates trace, with sufficient resolution, the geographic coordinates of the trajectory to be described. With the aid of so-called map matching, other road users may project the coordinate sequence onto their digital map and therefore deduce the transmitted trajectory. This produces the advantage that in principle, using a suitably high sequence length and resolution, the shape of the trajectory may be simulated as accurately as needed, in order to suitably transmit this. In this context, however, there is the disadvantage that in map data of different manufacturers, the coordinates of like road sections are not forced to include geographic coordinates, and the accuracy is normally approximately 30 meters. Thus, map matching to the exact street is generally not ensured. In addition, the risk of erroneous map matching exists, and a high sequence length of point coordinates is required in order to reduce this risk.
However, since some adjacent road sections run in parallel, this approach does not necessarily lead to a destination and is therefore not reliable. In addition, in order to simulate a trajectory for obtaining a reasonably high map matching score, a multitude of point coordinates, typically, approximately 30 to 50 point coordinates, may be required for a respective microscopic trajectory. In this manner, the transmission of several probable trajectories generates a relatively large quantity of data. When using the customary WGS84 coordinates, 100 point coordinates already generate a net of 800 bytes of data. When using C2X communication by means of IEEE 802.11p for transmitting the data, such a packet size may already be considered critical. The possible trajectories have a high probability of including significant redundancies.
The standard SAE J2735—Dedicated Short Range Communications (DSRC) Message Set Dictionary, is known as a further transmission standard, and this standard is specified for directly predicting a vehicle trajectory via the DF_PathPrediction element with a data field. It is made up of a specification regarding the current steering angle. Consequently, this produces the advantage that this standard may be made available, in essence, for predicting the future track, but this prediction is also not sufficient for determining the microscopic travel route.
The AGORA-C-Standard (ISO 17572-3) is known as a further standard and defines a methodology, which allows relatively reliable position referencing independently of the specific, underlying digital map. In addition to the WGS84 coordinates, attributes specific to the traffic network, such as road class and direction of the corresponding road section, are used. Individual points of the road network, as well as road sections or entire regions of a road network, may be referenced. An AGORA-C referencing of an individual point typically has a data size of less than 50 bytes, while the referencing of road sections consisting of a few kilometers may take up considerably more than 100 bytes. This achieves the advantage that relatively reliable referencing of predicted microscopic routes is provided; however, this is also associated with the disadvantage that the critical data size may be reached rapidly when several possible microscopic routes are transmitted, and the selection is limited to a few possible trajectories.